The present invention relates to a dry processing apparatus such as a film forming apparatus or etching apparatus, and a dry processing method.
A CVD (chemical vapor deposition) apparatus, which is an example of the dry processing apparatus, is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 10-70088. In this CVD apparatus, a liner made of an insulating material is provided between the main chamber and a pumping flow path arranged around the chamber, for the purpose of shutting heat or plasma. Thus, the generation of a precipitate in the pumping flow path is suppressed.
In the above-described CVD apparatus, a process gas flows through a nozzle of a shower head to a chamber of a processing region. The process gas flown into the chamber traverses an edge of a wafer placed on a lower electrode to flow outwards in a radial direction of the wafer, and goes over a centering situated at a ring-like shelf portion formed on the outer circumference of an upper section of the lower electrode. Then, the gas flows into the pumping flow path, and proceeds through the outer circumference of the processing chamber. After that, the gas is exhausted by a vacuum pump device connected to the process chamber.
In such a CVD apparatus, when the film forming process is continued, depositions accumulate on the inner wall of the chamber or in the pumping flow path, and thus an unevenness is created in the electro-conductivity of the chamber and the flow of the gas. As a result, the surface of a thin film formed on the wafer is adversely affected in terms of evenness or the like. In order to avoid this, when depositions accumulate to have a certain thickness or more in, for example, the vicinity of the lower electrode in the chamber, it becomes necessary to remove such deposition by cleaning with the process gas which is made to flow. Such a cleaning operation is carried out periodically.
However, between the film formation and cleaning, the flow rate of the process gas, the distance between the shower head and the lower electrode, and the like varies, and therefore the flowing manner of the process gas varies to become uneven, and there created some sections in the pumping flow path, where they cannot be easily cleaned. Therefore, drawbacks such as that a cleaning time is prolonged and dusts are easily created in sections in the pumping flow path, where the gas flow is stagnant.
Further, when the introduction of the process gas is stopped just after the completion of the process and the gas is exhausted to ultimate pressure, the gas exhaustion becomes, in some cases, uneven depending upon the position of the exhaust outlet, thus unsettling the gas flow rate distribution. For this reason, dusts generated in the space above the wafer during the process pass above the wafer for a long distance until the ultimate pressure is obtained by exhaustion, and therefore the probability that dusts attach onto the surface of the wafer increases.
Meanwhile, there is a CVD apparatus having a chamber in which a lower electrode on which a wafer is placed, is contained, and a gas introduction path is provided for the upper section of the chamber, whereas an exhaustion hole is made in the lower section thereof. In such the apparatus, an exhaustion plate having a plurality of exhaustion holes is provided at a central portion of the chamber so as to uniform the gas flow around the wafer. However, this technique entails a drawback in which depositions are attached to the exhaust plate, thus making the time required to remove the depositions longer. Thus, the utility of the process gas is low.
Further, dusts and the like, which are created from peeled-off depositions once attached to the surface of, for example, the inner wall of the chamber, attach to a wafer being subjected to film formation.
In the meantime, another example of the dry process apparatus is an etching device, which generates activated species such as of radicals or ions by plasma generated by exciting the process gas (medium gas), and carries out the etching of the wafer, which is an object to be processed.
As shown in FIG. 25, the etching apparatus 301 has a chamber 302, into which a process gag such as fluorocarbon is introduced, for example, over the upper end side, from a gas supply tube path 303.
In the chamber 302, a process stage 305 is provided as a holding means for holding a wafer W. The process stage 305 is designed to hold a wafer W with its upper end surface, and the holding section which holds the wafer W serves as a lower electrode 306. To the lower electrode 306, an RF power 307 provided on an outer side of the chamber 302 is electrically connected, so as to make it possible to apply a high-frequency voltage to the lower electrode 306.
In a lower side of the chamber 302, a gas exhaust pipe path 308 for exhausting a gas introduced to the chamber 302 and for maintaining the inside of the chamber at a predetermined pressure, is provided. The gas exhaust pipe path 308 is connected to a suction means, which is not shown, thereby the interior of the chamber 302 can be vacuum-suctioned.
In such an etching apparatus 301, the process gas introduced from the gas supply tube path 303 is excited into plasma by the RF power 307 which applies power to the lower electrode 306, and the activated species such as activated atoms (radicals) and ions, generated by the plasma, are carried by the gas flow directed to the gas exhaustion pipe path 308, thereby processing the wafer W placed on the lower electrode 306.
In usual cases, the gas flow rate within the apparatus is high on the exhaustion side, and therefore the etching rate is biased within the surface of the wafer W in some cases, depending upon the type of the process.
Further, as to the relationship between the gas flow rate and the etching rate on the surface of the wafer W placed in the process chamber, the process gas supplied from the gas supply inlet into the process chamber is allowed to pass above the surface of the wafer W placed on the lower electrode 306, and then exhausted from the gas exhaust pipe path 308. With this structure, the flow of the process gas on the surface of the wafer W is faster on the exhaust pipe path 308 side, whereas it is slower on the opposite side. In processes in which activated species are sufficiently supplied, the etching rate within the surface can be made uniform. However, in processes with an insufficiently amount of activated species generated, a great number of activated species move across the section where the gas flow is fast, thus increasing the etching rate there. As a result, the etching amount becomes uneven.
In order to prevent such an unevenness of the etching amount, the following technique has been proposed. That is, a baffle plate 309 is provided at a position between an circumferential wall of the process stage 305 in the chamber 302, and the inner wall of the chamber 302 so as to uniform the gas flow by suppressing the bias of the gas flow, which occurs due to the position where the gas exhaustion pipe path 308 is situated, and to restrict the passing of the plasma (charged particles) to the exhaust pipe path 308 side.
The baffle plate 309 is designed to be situated between the circumferential wall of the process stage 305 and the inner wall of the chamber 302, and therefore it has a ring-like shape. Further, the baffle plate 309 has slits 310 formed therein to be directed outwards from the center of the diameter of the ring-like shape. Each slit 310 is formed to have such a width that it is no more than two times the sheath thickness of the plasma generated within the chamber 302, and this structure prevents plasma from being exhausted as it is allowed to pass the exhaust pipe tube 308.
The cross sectional shape of each slit 310 is as shown in FIG. 26, and it is designed that the width is made narrow on one surface side (upper side in the figure), whereas the width is made wide on the other surface side (lower side) so as to be able to suction the process gas efficiently. As a result, the cross sectional shape of the baffle plate 309 has approximately a T-letter shape as can be seen in FIG. 26. Such a slit 310 is made over the entire circumference of the baffle plate 309 at a predetermined pitch.
However, since fluorine-based compounds such as CF4 and CHF3 are used in etching, fluorocarbon generated by recombination of activated species which were once decomposed, and product materials generated in etching reactions adhere to the inner wall surface of the chamber 302 and the baffle plate 309. Therefore, when the dry process device is operated for a long period of time, product materials are deposited on the upper section of the baffle plate 309 as shown in FIG. 27 along with time, and eventually slits 310 made in the baffle plate 309 are filled with the deposition of the product materials.
When the filling of the slits 310 due to the attachment of the product material, occurs, the gas pressure the discharge section increases along with time elapse, and therefore the processing conditions vary due to the increase in the gas pressure. If the processing conditions vary in this manner, problems such as an unevenness of the etching rate and variation of the rate are created.
In order to avoid this, the baffle plate 309 is removed from the interior of the chamber 302 periodically, and subjected to cleaning. However, it requires 5 hours or more from the replacement of the baffle plate 309 to the start of the operation of the dry processing apparatus, and therefore there is a great demand of a baffle plate which requires replacement less frequently and a shorter cleaning time.
The first object of the present invention is to minimize the area to where deposition materials attach, and to carry out the elimination of the deposition materials in an efficient manner, regardless of the process gas used, process condition, the structure of the process chamber, or the change in the pressure in the chamber.
The present invention is a dry processing apparatus including: holding means for holding a substrate to be processed in a chamber; gas supply means, provided to face a surface of the holding means, on which the substrate to be processed is placed, for supplying a process gas to the substrate to be processed, placed on the holding means; and a pumping flow path formed to surround an outer circumference of the holding means, wherein a pumping gap section for communicating a processing space formed between the holding means and the supply means, and the pumping flow path with each other, is made such that a width of the gap section differs between an exhaustion outlet side where the pumping flow path is connected to an exhaustion outlet, and an opposite side thereto.
According to the present invention, the pumping gap portion through which the process gas flows, is controlled on the exhaustion pump side and the opposite side, and therefore the flow of gas during the film formation can be made similar to that of the cleaning. In this manner, the cleaning can be carried out assuredly at a section to be cleaned, and the removal of dusts created can be accurately carried out. Further, the time required for these operations can be shortened.
Further, with the above-described structure, the distance in which dusts generated in a space above the wafer during the process pass over the wafer when the gas is exhausted to the ultimate pressure becomes minimum. In addition, the wall surface and the like, other than the counter electrode to which deposition materials and particles attached, are separated from the wafer by slits. Therefore, the probability that dusts attach to the wafer can be decreased.
The second object of the present invention is to realize a uniform exhaustion which is not influenced by the position of the exhaust outlet, and thereby to uniform the etching rate.
The present invention is a dry processing apparatus including: holding means for holding a substrate to be processed in a chamber; gas supply means, provided to face a surface of the holding means, on which the substrate to be processed is placed, for supplying a process gas to the substrate to be processed, placed on the holding means; and an exhaustion outlet for exhausting the interior of the chamber, wherein a block plate for covering the exhaustion outlet is provided on an upstream side of the exhaustion outlet.
According to the present invention, with the block plate, the uniformity of the etching rate within the surface can be significantly improved, and therefore an effect that, for example, the process is stabilized to improve the yield in the apparatus manufacture, can be obtained.
The third object of the present invention is to prolong the time up to which a slit is filled with the deposition material produced during process.
The present invention is a dry processing apparatus including: a chamber having an interior to which a process gas is supplied, holding means for holding a substrate loaded in the chamber; exciting means for exiting the process gas into plasma; and a baffle plate for partitioning the interior of the chamber into a processing space and an exhausting space, wherein an opening area of an opening made through the baffle plate in a surface of the processing space side is made larger than an opening area in a surface of the exhaustion space side.
According to the present invention, the opening area of the opening in the surface of the processing space side is made larger than the opening area in the surface of the exhaustion space side. With this structure, the opening of the end portion on the process gas introduction side, where deposition materials mostly easily attach, is made wide. Consequently, it requires a longer time until the opening is filled by the deposition of the produced materials during process, and thus the interval between periodical maintenance works of the baffle plate can be prolonged.
Therefore, it becomes possible to carry out the plasma process for a long period of time, thus enabling the improvement of the substrate producing performance. Further, the cost required for the maintenance can be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.